Vibration wave motor

Abstract

A vibration wave motor for generating a travelling vibration wave in a vibration member by applying a periodic voltage to an electro-mechanical energy transducer. An anti-movement device is provided to contact the vibration member at a pitch not equal to a multiple of nλ/2, where n is an integer and λ is the wavelength of a vibration wave so that the vibration member is prevented from rotating without reducing the drive efficiency of the motor.

We claim: 
     
       1. A vibration wave motor for driving a movable member by a travelling vibration wave having a wavelength λ generated in a vibration member by applying a periodic voltage to a phasically arranged or polarized electromechanical energy transducer, comprising: anti-movement means contacting said vibration member at a pitch not equal to a multiple of nλ/2, where n is an integer.   
     
     
       2. A vibration wave motor according to claim 1 wherein said pitch is equal to nλ/4, where n is an odd number. 
     
     
       3. A vibration wave motor according to claim 1 wherein said vibration means has a plurality of slits normal to the direction of travel of the vibration wave, and said anti-movement means engages the slits at said pitch. 
     
     
       4. A vibration wave motor according to claim 1 wherein said vibration member is of a ring shape. 
     
     
       5. A vibration wave motor according to claim 1 wherein said electro-mechanical energy transducer is an electrostrictive element. 
     
     
       6. A vibration wave motor according to claim 1 wherein said electro-mechanical energy transducer is a piezoelectric element. 
     
     
       7. A vibration wave motor for driving a movable member by a travelling vibration wave having a wave length λ generated in a vibration member by applying a periodic voltage to a phasically arranged or polarized electro-mechanical energy tranceducer, comprising: (a) said vibration member having a plurality of slits normal to the direction of travel of the vibration wave; and   
     
     
       (b) anti-movement means contacting said vibration member to engage the slits. 
     
     
       8. A vibration wave motor comprising: (a) electro-mechanical energy conversion elements;   (b) a vibration member for generating a travelling wave when an electrical signal is applied to said conversion elements, said vibration member having one surface thereof divided into a plurality of perpendicular extended projections from a plane of another surface of said vibration member; and   (c) anti-movement means contacting the projections of said vibration member for preventing the movement of said vibration member.   
     
     
       9. A vibration wave motor according to claim 8, wherein said vibration member is of a ring shape. 
     
     
       10. A vibration wave motor according to claim 9, wherein said anti-movement means is of a ring shape. 
     
     
       11. A vibration wave motor according to claim 10, wherein said anti-movement means have at least one projection engaged with the projection of said vibration member. 
     
     
       12. A vibration wave motor according to claim 11, wherein the projection of said anti movement means is inserted between projections of the vibration member.